This invention relates to a reverse thrust bucket for a jet drive and more particularly to a reverse thrust arrangement for a water jet propulsion unit.
Water jet propulsion units have a number of advantages over more conventional propeller type watercraft. In order to operate in reverse direction, it has been the practice to provide a reverse thrust bucket that is mounted on the discharge end of the jet propulsion unit for movement between a normal forward drive position and a reverse drive position. In the reverse drive position, the reverse thrust bucket redirects the flow of water from the jet propulsion unit discharge into a forward direction for generating a reverse driving thrust.
Generally these reverse thrust buckets include a surface that is adapted to be brought into confronting relationship with the discharge opening of the discharge nozzle for redirecting the water flow. It is important that the reverse thrust bucket establish a good sealing relationship with the discharge nozzle when in the reverse thrust position so as to improve the operating efficiency of the jet drive. To achieve this, it has been the practice to provide an offset flange at the surface of the reverse thrust bucket that is adjacent the upper end of the discharge nozzle when the reverse thrust bucket is in its reverse drive position. As a result, the surface of the reverse thrust bucket has a first portion that achieves the reverse thrust operation and a second, angularly related portion, that achieves the seal.
However, this angularly related portion provides not only drag when operating in the forward drive mode, but also generates a force that resists the movement of the reverse thrust bucket between its forward drive position and its reverse drive position. This gives rise to the necessity of employing considerable force on the reverse thrust bucket to move it between its positions.
It is, therefore, a principal object of this invention to provide an improved reverse thrust arrangement for a water jet propulsion unit.
It is a further object of this invention to provide an improved reverse thrust bucket and discharge nozzle arrangement for a water jet propulsion unit that will achieve good sealing in the reverse thrust mode while, at the same time, providing minimum flow resistance when operating in a forward mode.
It is a further object of this invention to provide an improved sealing arrangement for a reverse thrust bucket that will not provide any flow resistance or significant resistance to movement of the reverse thrust bucket between its positions so as to permit ease of operation.